When Schauman was attacked by an 8-to-10-ft. bull shark, she said, "it felt like a truck had slammed into me, then I felt a compacting squeeze and an acute burning in my left hand and my left leg.". Robert Hueter, director of the Center of Shark Research says " The bull shark is an ambush type of predator, it/which makes this big mortal wound."

I would like to know which is correct.
If "it" is correct, I wonder why "which" is wrong.
1. it makes this big mortal wound.
2. which makes this big mortal wound.

" The bull shark is an ambush type of predator, it/which makes this big mortal wound."
This sentence would be correctly written:
The bull shark is an ambush-type of predator which makes this big mortal wound.
or
The bull shark is an ambush-type of predator; it makes this big mortal wound.

Both will work. But "it" works better. I can't quite formulate why as yet.

There are a couple of things that occur:
1. "it" comes across as more dramatic and clearly refers to the shark.
2. "which" leaves you fumbling between "is which saying it is the shark that has done this" and "is which saying all ambush type predators create this type of wound". And in that fumbling the drama of the statement has been lost.

Stylistically, I prefer "it", either at the start of a new sentence or, as gdwdwrkr suggests, after a semicolon.

If "which" is used, there are a couple of problems:

Does the relative pronoun refer to the bull shark or the word "predator".

In either case, is the relative clause "defining" or "non-defining".

The first question can only be answered by the person who made the statement. It cannot be resolved by syntax or context (in this case).

The second question is resolved by whether you use a comma before "which" (or pause slightly before "which" when speaking):

The bull shark is an ambush type of predator, which makes this big mortal wound.
If the "which" is intended to refer to the "predator", or more accurately, the "ambush type of predator", this means that all "ambush types of predator" make this big, mortal wound.
If the "which" is intended to refer to the "bull shark", this means that all "bull sharks", but not necessarily all "ambush types of predator" make this big, mortal wound.

The bull shark is an ambush type of predator which makes this big mortal wound.
If the "which" refers to "ambush type of predator", it means that not all ambush types of predator make these wounds, but the bull shark is one type that does.
It is highly unlikely that the "which" in this "defining" variant will refer to the "bull shark", as a defining relative clause will invariably immediately follow the noun or noun phrase it refers to.

In other words, several different versions could be correct, depending on what the speaker actually intended.